Process for increasing the transparency difference of sound records in multilayer materials



V Patented Feb. 8, 1944' ITED STATES, P A 'l-ENT- OFFICE PROCESS FOR INCREASING THE 'TRANS- PARENCY DIFFERENCE OF SOUND REC- ORDS IN MULTILAYER MATERIALS Wilhelm Schneider, Dessau, and Norbert Senger, Dessau-Haideburg, Germany; vested in the Alien Property Custodian No Drawing. Application February 17, 1942, Se-

. rial No. 431,269. In Germany September 19,

Claims. (01. as -5) the sound record are not or only slightly attacked. In fact, with different concentrations the silver-bleaching agents show widely diflering 80 lution velocities for the colloidal silver of the filter or ant-halation layers and for the granular silver of the sound record. For each material it is .possible to determined the concentrations and period of action for the bleaching of the colloidal layers without causing material attack of able soimd reproduction 'is reached in seaming with the usual photo-cells. In many cases color films having sound records are worked up such that the sound track is wholly or partly formed from silver. Thissilver sound track itself may be used for thereproduction or it may be intensified in known manner or transformed into other compoimds impermeable to infra-red rays as, for instance, metal complex salts.

In the manufacture of multi-color images or multi-layer material it is also known to use filter layers or anti-halation layers which contain colloidal silver. with such material one obtains a sound track the blackened parts of which consist of silver or silver and dyestuffs and the nonblackened parts of which contain silver uniformly the granular silver of the sound record.

For multi-layer materials for the production of color-images with, sound records such layers are especially suitable as contain non-dlifusing dye-. stuff formers as, for instance, described in the journal: Photographische Korrespondenz," 1988, page 21, and 1939, page 106. Thefilter layers may, for instance, be produced by the process disclosed in U. 5. Patent 2,220,187.

distributed in the filter layer or anti-halation' layer. These silver layers already absorb infrared rays perceptibly. Since the volume of sound is determined by the transparency difference, but the transparency as a logarithmical function of the density decreases more quickly in the regions of low density than it does-in those of higher density, the additional absorption uniform per se of the filter layers or anti-halation layers results in a reduction of the transparency difference and hence of the maximum volume of sound in the regions of 'low density. As to the usual' -methodsof intensifying or converting the silver sound track the, silver filter layers or anti-halation layers naturally have the same chemical behavior as the silver sound record,-i. e., the filter oranti-halation layer is, for instance, modified in the same way as the silver record whenan intensifier is used. The transparency of the unexposed parts again decreases more strongly than that of the exposed-parts does so that an additional loss of sound intensity is effected.

Our present invention is based onjthe observation that these disadvantages "are avoided by The production of the sound track and the color image may be carried out in various ways as, for

instance, by theprocesses described'in U. 8. Patents 2,220,178, 2,178,882, 2,235,033, 2,232,056 and The following example illustrates the invention but is not intended to limit it thereto.

Example The silver sound track film of a photographic multi-layer material in the several emulsion layers of which the color component images have been produced by reacting non-diffusing dyestufi formers with an aromatic amino developer and which contains a yellow filter layer and an anti-' 1 halation layer with colloidal silver is treated with treating the sound track with a solution ,of a substance capable of bleaching silver of such a concentration and for such a duration that the colloidal silver of the filter .or anti-halation la ers is dissolved, but the granular silver particle of a solution consisting of 4 g. oi. potassium ferricyanide and 1000 cc. of water for 15 minutes.

The transparency din'erence which was 0.11 before treatment is 0.24 after the'treatment. The.

increase of sound intensity is 6.8 db.

We claim: v 1. A process for increasing the transparency I difi'erence of sound records on color photographic niulti-layer materials having at least one filter layer containing colloidal sliver which process comprises treating the sound track with. a solution of a substance capable or bleaching sliver of such a concentration and forsuch a period that said colloidal silver of the filter layers is dissolved but the granular sliver of said sound record is not or only slightly attacked.- I

2. A process for increasing'the transparency difference of sound records on color photographic multi-layer materials having atleast one filter layer and an anti-halation layer, saidlayers con-.-

taining colloidal silver which process comprises.

stance capable of bleaching silver of such a concentration and for such a period that said colloidal silver of the layers is dissolved but the granular silver of said sound record is not or only slightly attacked.

3. The process as defined in claim 1 wherein the substance capable of bleaching silver is an alkali metal ferricyanide.

4. The process as defined in claim 1 wherein to treating the sound track with a solution of a sub- 

